Currently, a sublimation transfer recording method is known, wherein a thermal transfer sheet in which a sublimation type dye is supported on a substrate made of a plastic film or the like, and a thermal transfer image-receiving sheet in which a receiving layer is provided on a substrate made of a paper, a plastic film or the like are superposed to form a full color image. Since this method uses the sublimation type dye as a color material, it is possible to adjust freely the density and the gradation dot unit by dot unit, a full-color image can be clearly expressed as the original image on the image-receiving sheet. Therefore, this method has been applied in the color image formation for digital cameras, video recorders, computers or the like. Its image can rival silver halide photography with high quality.
In order to obtain good printing properties on the thermal transfer image-receiving sheet to be used for the sublimation transfer recording method, it is known that it is preferable to give heat resistance and cushioning to the thermal transfer image-receiving sheet. With regard to the functional requirements for the heat resistance and the cushioning, a thermal transfer image-receiving sheet in which a foamed film such as a polypropylene film having micro-voids is laminated onto the substrate and the receiving layer is provided on the foamed film has been proposed. However, this thermal transfer image-receiving sheet will have problems such that the foamed film shrinks by heat on the formation of the receiving sheet and thus curls. Thus, the studies for providing a novel functional layer having the heat resistance and the cushioning functions, and the studies for a thermal transfer receiving sheet in which a laminated film such as the foamed film is not used in order to eliminate the curl due to the thermal history during the manufacturing process have been made. For example, Patent Document 1 proposes a thermal transfer image-receiving sheet which is provided with a porous layer instead of the foamed film, wherein the porous layer is formed by using a coating liquid which contains hollow particles and a binder.
Incidentally, since the hollow particles contained in the porous layer is soluble to the solvent, in the case that the receiving layer is formed on the porous layer with using an organic solvent-type coating liquid, the porous layer is destroyed. Because the hollow particles are dissolved in the solvent. Thus, the functionality as the porous layer is no longer maintained. Under such a situation, a thermal transfer receiving sheet in which a barrier layer made of polyvinyl alcohol is provided between a porous layer and a receiving layer has been also proposed, said polyvinyl alcohol is known as a resin having a high solvent resistance. It is said that the destruction of the porous layer's functionality by the solvent can be prevented when the thermal transfer receiving sheet having this barrier layer is adopted.